The present invention relates to aqueous-based cleansers for glass, particularly for windows, mirrors and reflecting surfaces which are free of builder salts and organic solvents. Hereinafter such cleansers will be referred to as "window cleansers."
Window cleansers, when used in the household, mostly come in contact with the skin of the hands of the user. They must therefore be correspondingly mild, that is, they should affect and cause as little as possible damage not only to the skin, but also to the areas surrounding the glass, of varnish, wood, leather, etc. Beyond that, they must be sufficiently effective to remove the grease-containing and pigment-containing dirt from window panes, mirrors, glass bricks, automobile windows, and similar reflecting surfaces. Finally, the cleaned surfaces should rapidly dry free of streaks, without requiring mechanical repolishing.
Such preparations generally contain ammonia and/or an organic surface-active compound of high wetting capacity in aqueous solution, to which water-soluble, organic solvents like low molecular weight aliphatic alcohols, glycols, glycol ethers or acetone are added.
From U.S. Pat. No. 4,101,456, corresponding cleansers are known which allow keeping glass surfaces spot-free during cleaning and rinsing, without separate drying. These are aqueous preparations which contain from 0.01% to 1% by weight of a water-soluble surface-active agent, and a water-soluble, non-proteinaceous cationic polymer with a molecular weight of 25,000 to 10,000,000, where the weight ratio of the surface-active compound to the polymer in the washing fluid is about 2:1 to about 1,000:1. With these preparations, however, it is recommended to rinse the glass surface before letting it dry (column 1, lines 42-44). This is not always possible when cleaning large glass surfaces in the household, for example, window panes in living areas, but which in any case is inconvenient. Another disadvantage of these cationic polymers is their incompatibility with many anionic compounds and therefore the customary addition of anionic surface-active compounds is greatly limited.
According to the teachings of U.S. Pat. No. 3,696,043, about 0.03% to 2% by weight of a soluble polymeric salts was therefore added to aqueous or aqueous-alcoholic window cleansers containing 0.01% to 5% by weight of a nonionic or anionic surface-active agent, and alkaline-reacting compound, if necessary, to give solubilizing salt groups. The polymeric acid consists of a copolymer of 1 to 2 mols of a monovinyl-aromatic monomer per mol of an unsaturated dicarboxylic acid or its anhydride. The polymeric acid is neutralized with a sufficient amount of ammonia, an alkali metal base or an amine to cause the formation of solubilizing salt groupings. This composition is said to reduce the formation of streaks on the cleaned surfaces and fogging at high humidity, and to impart to them a dust-repelling finish.
These preparations which contain the polymer salts claimed there in the lower amounts of the claimed concentration range, have a good antifogging effect on slightly soiled window panes or mirrors, but they have a very low cleansing effect. On naturally soiled windows, which have been exposed on the inside to cigarette smoke or central heating air, and on the outside to the exhaust air of heavy street traffic, the cleaning power is by far inadequate. The result is smearing of the dirt components not absorbed by the liquor on the pane surface, so that a film or streaks remain after cleaning, hence unsatisfactory cleaning. If the content of polymer salt is increased, on the other hand, but still within the claimed concentration range, the removal of dirt is improved, but residues from the cleaning liquor remain on the glass surface. These residues cannot be removed by dry polishing, and it is therefore necessary to rinse with clean water.
According to the teachings of U.S. Pat. No. 3,939,090, 0.01% to 0.1% by weight of a copolymer of an ethylenically-unsaturated dicarboxylic acid anhydride or partial ester thereof with an ethylenically-unsaturated monomer that is free of carboxyl groups, are added to window cleansers to improve their cleaning action, which copolymer can have a molecular weight of about 400 to about 2,000,000. The addition of solvents is absolutely necessary for the preparation to display its full activity.